October Eating
You're hungrier in October.
The biology predates everything
you've been told about food.
On leptin, ghrelin, the serotonin-carbohydrate pathway, and why your appetite in autumn is a seasonal signal — not a character failing.
October hunger is not a character flaw. It's not a sign that your diet needs adjusting, that your willpower is failing, or that you've lost the thread you managed to hold through September. It is a biological response that was being shaped by photoperiod long before anyone invented the word "wagon" — or the concept of falling off one.
Two hormones are at the centre of what happens to appetite in autumn: leptin and ghrelin. Understanding them doesn't resolve everything about how you eat. But it changes the frame entirely. And changing the frame is where I always want to start.
Leptin: the satiety signal that autumn quiets
Leptin is produced by adipose tissue — fat cells — and circulates roughly in proportion to your body's energy reserves. Its primary function is to signal the hypothalamus that stores are adequate: energy is available, food intake can moderate, activity can continue. In the shorthand version: leptin equals satiety.
But leptin sensitivity — how clearly the hypothalamus receives and acts on that signal — is not fixed. It varies with sleep quality, with inflammation, with stress. And it varies with season.¹
As days shorten and melatonin windows expand, studies in seasonal mammals have shown consistent reductions in hypothalamic leptin responsiveness: the same circulating leptin levels produce a weaker satiety signal. The food intake required to feel genuinely satisfied rises. You can have adequate leptin in circulation and still feel hungry, because the signal is landing less clearly than it did in July.
In humans, this mechanism is attenuated compared to seasonal breeders — but it is present. Seasonal variation in caloric intake has been documented across multiple populations, with autumn and early winter consistently showing the highest average food intake of any season, regardless of cultural variation in food availability. This is not coincidence. It is a coherent physiological response to a changing photoperiod.
Ghrelin: the hunger signal that responds to darkness
Ghrelin is produced primarily by the stomach lining. It rises in the hours before meals and falls after eating. It is your body's active hunger signal — the "time to find food" hormone — and it is strongly circadian: it follows a predictable daily rhythm tied to both meal timing and light exposure.
In autumn, that rhythm shifts. The evening ghrelin peak — which exists in summer but resolves with dinner — becomes more pronounced and more sustained. Longer darkness, earlier melatonin onset, and the metabolic shift toward energy storage that prepares the body for winter all contribute to an evening ghrelin profile that keeps hunger active later into the night.
This is why you find yourself in the kitchen at 8pm in October in a way you wouldn't have been in July. Your ghrelin is doing exactly what it evolved to do: ensuring you accumulate enough energy to survive the coming months of historically lower food availability. The fact that you live in the 21st century with a supermarket nearby does not update the hormone. It is running a programme that is several hundred thousand years old.
The serotonin-carbohydrate connection: why it's specifically bread
The third piece of the October appetite puzzle explains not just the volume of hunger but its specificity. It's not only that you're eating more in autumn — it's that you specifically want carbohydrates. Bread, pasta, potatoes, sweet things, starchy comfort foods. This is not random and it is not weakness.
Serotonin synthesis in the brain requires tryptophan, an amino acid that competes with other large neutral amino acids for transport across the blood-brain barrier. Carbohydrate intake triggers an insulin response that clears competing amino acids from the bloodstream, giving tryptophan preferential access to the brain and temporarily increasing serotonin synthesis. Wurtman and Wurtman documented this relationship carefully: carbohydrates consumed without significant protein produce a measurable increase in brain serotonin levels.³
In October, when light deprivation is putting downward pressure on serotonin synthesis — serotonin production is stimulated by light and suppressed by darkness — the body's drive to seek carbohydrates becomes a form of neurochemical self-regulation. You want pasta at 7pm because your brain is trying to make serotonin.⁴ It knows what it needs. It is asking for a specific substrate.
This mechanism is more pronounced in people who experience seasonal affective disorder — in whom carbohydrate craving is a documented and well-characterised symptom — but it operates to some degree in everyone whose serotonin system is sensitive to light.⁵ The difference between someone who craves carbohydrates in autumn and someone who doesn't is often a difference in serotonin sensitivity, not character.
Move your cursor across the chart above to read what your appetite hormones are doing at each hour of the day — and where October diverges most sharply from summer.
What the divergence actually means
The chart above has a particular moment worth dwelling on: the late afternoon. Around 4 to 6pm, the two curves — summer and October — separate most dramatically. This is not arbitrary. It is the hour when afternoon light is falling fastest, when serotonin synthesis begins dropping in response to reduced light stimulation, and when ghrelin's evening rise collides with a serotonin system that is increasingly depleted.
This window is the heart of October eating. It's when the carbohydrate craving is sharpest. It's when the pull toward comfort food is most insistent. And it is, in every biological sense, your body doing its job — reading the season, responding to the signal, seeking the substrate it needs.
The problem is not that the signal fires. The problem is the cultural layer that sits on top of it: the idea that this pull should be resisted, that giving in to it is failure, that October appetite is a disorder to be managed rather than a seasonal response to be respected.
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The industry that profits from your October hormones
The wellness industry has a straightforward relationship with October hunger: it sells to it. Autumn reliably produces a wave of "reset" content, detox programmes, and clean eating campaigns — very carefully timed to coincide with exactly the moment when your leptin sensitivity is lowest, your evening ghrelin is most persistent, and your serotonin is under the most seasonal pressure.
This is not coincidence. The conditions that make October the most biologically challenging time of year to eat in the way mainstream wellness prescribes are precisely what make it the most commercially productive time of year to sell you something that promises to fix it. The worse you feel about your appetite, the more programmes you buy. The more programmes you buy, the worse you feel when they don't work against a seasonal signal that predates the concept of a wellness programme by several hundred thousand years.
The biology of seasonal appetite is not a design flaw. It is ancient, purposeful, and consistent across populations and across centuries. What would actually help is being told that — instead of being offered a subscription to correct it.
What to actually do with this
This is not a piece about eating freely in October and ignoring all other considerations. It's a piece about understanding the biological system well enough to work with it rather than against it — which is a very different thing from having no relationship with your food at all.
- Don't restrict in the evening. The October evening ghrelin peak is real and biologically driven. Fighting it with restriction tends to amplify it — restricted leptin levels fall further, ghrelin rises in response, and the urge intensifies rather than resolving. A satisfying dinner with adequate carbohydrates is responsive eating. It is not failure.
- Front-load protein in the morning and early afternoon. Protein earlier in the day doesn't eliminate the evening appetite surge — nothing eliminates a seasonal hormonal signal — but it does reduce its urgency. Adequate protein earlier provides satiety through a different mechanism than the serotonin-carbohydrate drive, giving the evening eating a less frantic quality.
- Take the carbohydrate craving seriously as neurochemical information. If you're craving bread at 7pm, your serotonin system is under pressure. Address the upstream signal: morning light exposure (the strongest stimulator of serotonin synthesis), physical movement earlier in the day, and adequate tryptophan from food — turkey, eggs, oats, dairy — in the hours before the craving window. This doesn't eliminate the craving, but it often reduces its insistence.
- Track your hunger patterns alongside your cycle. Leptin and ghrelin both interact with cycle hormones. The luteal phase, in particular, tends to amplify the seasonal appetite shifts — higher evening ghrelin, more pronounced carbohydrate craving, reduced morning satiety. Tracking hunger patterns alongside your cycle phase across one autumn can show you your specific seasonal-hormonal profile, rather than the general population average.
- Be actively suspicious of October wellness content. The months with the most published content about eating less are September, October, and January — the months when appetite hormones are most persistently activated. This is a pattern worth noticing. The content is not wrong because it tells you to pay attention to what you eat. It is wrong when it frames your seasonal biology as a problem you caused.
The hunger that arrives in October was always going to arrive. It arrived for your grandmother, and for her grandmother, and for every woman before them who moved through autumn in a body that was designed to register the changing light and respond accordingly.
What's new is not the hunger. What's new is the culture that tells you it's a problem — and the industry that profits from your attempts to solve it.
Your appetite in October is data. It's telling you something about your serotonin, your ghrelin timing, your leptin sensitivity, your readiness for the season ahead. The most useful thing you can do with that data is read it — and stop confusing a seasonal signal with a personal failing.
– Nina- Kershaw, E.E., & Flier, J.S. (2004). Adipose tissue as an endocrine organ. Journal of Clinical Endocrinology & Metabolism, 89(6), 2548–2556. doi:10.1210/jc.2004-0395
- Tschöp, M., Smiley, D.L., & Heiman, M.L. (2000). Ghrelin induces adiposity in rodents. Nature, 407(6806), 908–913. doi:10.1038/35038090
- Wurtman, R.J., & Wurtman, J.J. (1995). Brain serotonin, carbohydrate-craving, obesity and depression. Obesity Research, 3(S4), 477S–480S. doi:10.1002/j.1550-8528.1995.tb00215.x
- Leibowitz, S.F., & Alexander, J.T. (1998). Hypothalamic serotonin in control of eating behavior, meal size, and body weight. Biological Psychiatry, 44(9), 851–864. doi:10.1016/S0006-3223(98)00186-3
- Rosenthal, N.E., Sack, D.A., Gillin, J.C., Lewy, A.J., Goodwin, F.K., Davenport, Y., Mueller, P.S., Newsome, D.A., & Wehr, T.A. (1984). Seasonal affective disorder: a description of the syndrome and preliminary findings with light therapy. Archives of General Psychiatry, 41(1), 72–80. doi:10.1001/archpsyc.1984.01790120076010